My Little Pony: Friendship is Magic S1 Ep5 "Griffon the Brush-Off"

Pinkie Pie and Rainbow Dash bond by playing pranks on the other ponies, but when Rainbow's old friend, Gilda the Griffon, shows up for a visit, Pinkie Pie becomes a third wheel. However, she soon notices Gilda displaying a mean streak towards other ponies. A Pinkie Pie-styled party may reveal who exactly is Rainbow Dash's true friend.